Scavenging internal-combustion engines



June 8 1926. 1,587,585

A. HANSEN ISICAVENGING INTERNAL COMBUSTION ENGINES I Filed July 19, 1924 Fi .1 Fig. 3.

'atented dune rare.

'Ufii @EN', DE BERLIN-DAHLEIVE, GERMANY, ASSIGNQR 'TO FRIED. KR'UPP GER- WERFT AlKTIENGESELLSGHAFT, 0F KIEL-GMRDEN, GERMANY.

SCAVENG-ING INTERNAL-GUWIBUSTIQN ENGINES.

flppltcation filed July 19, 1824, Serial No. M7355, and in Germany July 20, 1923.

The invention relates to two-stroke exlosion or constant pressure internal comustion engines in which the scavenging is efiected through scavenging ports and in which the charging mixture or the scavenging air is let in and out through controlled or non-controlled ports. Tn carrying out the scavenging process with engines of the character stated, it is important to have the fresh charge or the scavenging air efiecting the scavenging of the cylinder, penetrating into the upper portion of the latter to a sufficient extent in order to completely ex e1 the exhaust gases out of the entire cylin er.

This eflect has hitherto been endeavored in a double manner. Firstly by influencing in the desired sense, by means of a substantially vertical deviating surface arranged on the front face of the piston, the scavenging air entering through the inlet ports and escaping on the Opposite side of the cylinder through the outlet ports, .or, secondly, by

superimposing the inlet and outlet ports at the same side of the cylinder and conveying the scavenging current in a closed circle over the front face of the piston along the cylinder wall and cover onto the outlet ports. Tn both cases mentioned the scavenging current is rectangularly deviated on a certain' point, from its direction; in the firstnamed case on its entering section at the deviating surface, in the second case, on its escaping section, at the outlet ports. This forcible change of direction, however, interferes with thecontinual flow of the scavenging current which is necessary for a satisfying scavenging effect, and requires an increase of pressure of the scavenging air 0W- in to the fact that, as it is well-known, these sudden changes of direction cause considerable losses in kinetic energy in every flowing process. Furthermore, the above-mentioned arrangement of a deviating surface on thepiston the effect of which seems besides to be rather doubtful, suifers from an unfavorable shape of the piston. The second scavenging method, of the closed circle of the scavenging air, involves, besides the drawbacks already mentioned, still the following disadvantages As the entering and the escaping air current must be led very close to each other on the inlet and outlet point, in order to not have the whole arrangement of the,

ports extending too much in height, a muthe entering mixture or charging air to-be pulled along with the exhaust gases through the outlet ports out of the cylinder. This fact involves aloss in charging mixture or air and therewith also in energy, as the en-' ergy producing this air current must be furnished by the engine itself, to. say nothing of the loss in fuel in explosion engines. Be sides, with the aforesaid mutual arrangement ofthe superimposed inlet and outlet ports the piston has to pass, on the return stroke, over the breadth of two ports before it will cut off the cylinder. This arrangement thus causes a considerable loss in stroke which may only be'compensated by employing controlled outlet ports. Finally in this scavenging method which takes place in a closed curve, a dead core of gases, rotating in itself, is formed which permanently remains in the cylinder and can be dissipated only by special measures, for instance by blowing an air current through this core.

Now the invention has for its'object to have a scavenging process in engines of the character stated which does not suffer from the drawbacks mentioned. This object is attained according to the invention by leading the charging mixture or the scavenging air in a closed current through downwardly inclined inlet ports situated as close together as possible in the circumferential direction of the cylinder, over the piston surface which is of concave shape, by leadin then this current up along the opposite cy 'nder wall and by splitting the current by disposing the outlet ports at both sides of the cylinder so as to cause the current to reach the outlet ports in two divergent partial currents, which ports penetrate. the cylinder wall and cause the scavenging current to escape in a continual flow without any forcible change of direction. I

The accompanying drawing illustrates an embodiment of the subject-matter of the invention byway of example,

Fig. 1 showing a longitudinal section through the cylinder constructed according engine,

. cle is Fig. 2 showing the cross section on line 2-2 of Fig.1;

Fig. 3 a longitudinal section through the cylinder on line 33 of Fig. 1; Fig. 4 is a detail. in section,

Fig. 5 diagrammatically shows the 'invention employed in a multi-cylinder engine.

A denotes the working cylinder and B the iston reciprocatng therein. In the cylinar wall are disposed the inlet ports a which have the shape of nozzles-and the two outer ports of which converge, Fig. 2, so that the entering scavenging air will conyeree also and stream in a closed current over the concave front face of the-piston. (In the embodiment of Fig. 4 the inlet ports are subd1- .vided by means of a guiding face a At approximately the same level as the inlet ports are so arranged the outlet ports a that they form two groups opposite each other, about on a diameter which is vertical with respect to the direction of entrance of the air, these outlet ports penetrating the cylinder'wall in the oblique direction shown in Fig. 2.

In case the ports are not controlled, the upper edge of the outlet ports a must be situated at a level hi her by the primary exhaust space 0: than t e up er edge of the inlet ports a, see Fig. 1. ith controlled ports the upper edges of the inlet and outat orts may lie at the same level.

file scavenging air, after having passed over the front face of the piston, raises in a broad current along the cylinder wall, oppositely to the inlet ports, then it returns on the to near the cylinder cover, and flows, in t e first likewise in closed current, downwards along the cylinder wall opposite tothe first-named wall. Owing to the bilateral arrangement of the outlet ports the current bifurcates, the two partial currents then flowing on both sides to'the exhaust orts and entering through these into the ex aust conduit. 7

The described method enables a radical scavengin action throughout all ortions of the cylin er. As the course of t e aircur rent is quite continual, losses in pressure, .as they may occur with the hown arrangements, cannot take place so that the scavenging ressure can be held comparatively low. Furt ermore, a rotating dead core of exhaust ases cannot arise since no closed cirt rmed. As the superimposed disposition of the inlet and outlet ports is entirely dispensed with, the described arrangement is, further, free from any loss in scavenging air, charging mixture and fuel, as it is inavoidable with the known arrangements.

Finally, the loss in stroke which in the known arrangement mentioned in second line exists due to the superimposition of the ports, is in the present arrangement dispensed with also.

The efi'ect of the guiding faces a is illustrated in Fig. 4. In the position shown of the piston which opened the inlet port by half its area only, the. air would enter, if no guiding face a were present, about in the direction of the dotted arrow. By providing said guiding face the air is caused to flow in the direction of the full line arrow so that even with partially opening the inlet port the scavenging current flows in a satisfyin manner.

W i th multi-cylinder engines the arrangement may be chosen, as shown in Fig. 5, in a manner such as to have the outlet ports fitting into two pipes C common to all the cylinders and extending along both sides thereof. In this case the air is conveniently supplied .by air chambers I) provided between the cylinders. This arrangement enables, besides a very small structural len th of the engine, to have very simple cylin er castings. Finally, a pair of cy 'nders may be connected to each air chamber D Claims:

1. In an internal combustion en ine cylinder, an inlet port in said cylin or for a scavenging medlum under pressure, and an outlet port in said cylinder circumferentially spaced from said inlet port, whereby the scavenging medium upon introduction into said cy in er executes a spiral loo therein, the burned gases being expelled thereby through said outlet port in a direction obtuse relative to the direction of the incoming current. V

2. In an internal combustion engine cylinder, a cover therefor and a piston therem, a downwardly directed inlet port in said cylinder for a scavenging medium under pressure, and an outlet port in said cylinder circumferentially spaced from said inlet port, whereby the scavenging medium upon introduction into said cylinder develops a current describing a spiral loop therein de termined b the piston face, the cylinder wall opposite said inlet ort, the cylinder cover, and the c linder wa 1 above said inlet port, whereby t e burned gases are expelled through said outlet port in a direction obtuse relative to the direction of the incoming current.

3. In an internal combustion engine cyl inder, an inlet port in said cylinder for a scavenging medium under pressure, and outlet ports in said cylinder 'circumferentially spaced from said inlet port at either side thereof, whereby the scavenging medium upon introduction into said cylinder executes an upward loop therein expelling the burned gases through said outlet ports in a 1 bifurcated current straddling the path of the incoming current, the directions of the out going currents being obtuse relative to the irection of the incomin current.

4. In an internal comiustion engine cylinder, a cover therefor and apiston therein, a downwardly directed inlet" port in said cylinder for a scavenging medium under pressure, outlet ports .lIl said cylinder circumferentially spaced from said inlet port at either side thereof, whereby the scavengin medium upon introduction into said, cylinder is deflected from the upper face of said piston to the wall of the cylinder opposite said inlet port, thence to the cylinder cover, thence to the cylinder wall above said inlet port, and thence in a bifurcated current straddling the incoming current toward the outlet are expelle through the latter in directions ports, whereby the burned gases obtuse relative to the direction of the incoming current.

5. In an internal combustion engine cylinder, a downwardly directed inlet port in said cylinder for a scavenging medium under pressure, and outlet ports in said cylinder circumferentially spaced from said inlet port at either side thereof, said ports lying in substantially the same lane, the axial lines of said outlet ports eing at obtuse angles relative to the axial line of said inlet port, as and for the purpose described.

The foregoing specification signed at Berlin, Germany, this first day of July, 1924.

ASMUS HANSEN. 

